In surgery, adhesions and scar tissue, formed in a patient's thoracic or abdominal cavity as a result of previous surgery, infection or trauma, frequently cause difficulties in locating, and gaining access to, the internal organs or structures that require repair or removal. For example, adhesions frequently cause problems in anterior and anterolateral access to the spinal column or the content of the abdominal cavity.
Typically, a surgeon releases adhesions manually, using a gloved finger. However, when a gloved finger is used, it is not possible to visualize the adhesions, and unnecessary bleeding, and tearing, or damage to the normal anatomy, almost inevitably occurs. In addition, access to certain organs requires the identification and separation of two muscle groups through their anatomical planes.
An endoscopic balloon tissue dissector can be used to achieve the above objectives, and various instruments incorporating inflatable balloons have come into use for tissue dissection. The balloon, incorporated at the distal end of an endoscopic instrument, is inserted between adjacent tissue layers, and inflated to separate those layers. Alternatively, for dissection with visualization, some surgeons have used an “optical trocar,” which comprises a tube having a system of lenses or a bundle of optical fibers for transmitting an image from the distal end of the tube to an eyepiece or to an electronic video monitor.
More recently, a surgical dissector has been developed which combines features of the balloon dissector and the optical trocar. Such an instrument is described in U.S. Pat. No. 5,607,441. In that instrument, a transparent, inflatable, dissecting balloon is provided at the distal end of a shaft, and an optical instrument, extending through the shaft into the interior of the balloon, enables the surgeon to visualize the dissection as it takes place.
Despite the advances in endoscopic surgery exemplified by U.S. Pat. No. 5,607,441 and numerous other patents, there remains a need for instrumentation that can achieve dissection of tissue and provide optimal access to a surgical site with minimal trauma to the patient.